Extraction method

ABSTRACT

Covers a method of separating a nonionic surfactant from an anionic surfactant by use of cyclohexanone.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method of extracting out certain sulfonatedorganic compounds from alcohols used to prepare said compounds.

2. Description of the Prior Art

Organic sulfonic acids and organic sulfonates are becoming increasinglyimportant due to their use in the preparation of liquid detergents, assurfactants for enhanced oil recovery processes and for other uses. Anumber of general schemes are available to sulfonate organic compounds.For example, sulfonated materials may be prepared by sulfonationprocesses employing concentrated sulfuric acid or oleum. Another methodof preparing organic sulfonates involves reacting an organic alcoholcontaining at least one hydroxyl group with a hydroxy-containing alkylsulfonic acid or salt thereof. Under appropriate conditions the twocompounds are condensed with formation of by-product water to produce anether sulfonate. This reaction can be termed a sulfoalkylation reaction.A typical sulfonating reagent here used to react with a wide variety oforganic alcohols is sodium isethionate, also named as the sodium salt of2-hydroxy ethane sulfonic acid.

In most instances it is necessary to separate out the sulfonate producedor anionic surfactant from the reaction mixture which normally containsunreacted starting materials such as he alcohol reactant. In the abovecase wherein an alcohol is reacted with a sulfonating agent such assodium isethionate usually an excess of alcohol is employed to assist indriving the reaction to completion. Thus, it is necessary to resolve themixture of starting alcohol material and final ether sulfonate, one fromthe other.

There are a number of ways available to effect such separation. However,with respect to surfactants of relatively high molecular weight usuallyan extraction technique is devised. The use of such extractants in theusual situation is at best an emperical type of science faced with muchunpredictability. For example, a class of extractant materials useful inseparating one group of nonionic surfactants from anionic surfactantsderived therefrom may be entirely useless in making a similarresolution, though of only a slightly different class of surfactants.

In other situations while a solvent may be found useful as an extractantin certain situations, such solvent while displaying proper selectivityand efficient partitioning may have other drawbacks such as itself beingunstable, or having a tendency to convert the materials being separatedto other derivatives by chemical reaction, which derivatives may becorrosive or have other undesirable properties. In still furtherinstances the proposed extractant with or without heat may causeformation of emulsions or gels. Lastly, while a solvent may be useful asan extractant, in many instances the solvent itself is difficult toseparate out from the material it has extracted, and in some cases isimpossible to do so.

it is therefore a principle object of this invention to provide a methodfor separating out ether sulfonates from organic alcohols from whichether sulfonates were derived through reaction with hydroxy-containingalkyl sulfonic acids or salts by means of a unique extraction technique,which process is free from the just-mentioned disadvantages of prior artprocesses.

The above-mentioned object and advantages of the present invention willbecome apparent as the invention is more thoroughly discussedhereinafter.

SUMMARY OF THE INVENTION

In its broadest aspects the present invention comprises a method ofresolving a mixture of a nonionic surfactant and an anionic surfactantexisting in an aqueous medium, said nonionic surfactant having astructural formula as follows:

    R.sub.2 OH

where R₂ is a radical selected group consisting C₁ -C₂₂ alkyl, C₁ -C₂₂alkenyl, C₁ -C₂₂ hydroxy alkyl, C₁ -C₂₂ hydroxy alkenyl, alkarylcontaining one or more C₁ -C₂₂ groups substituted on said aryl group,aralkyl containing 7-22 carbon atoms, and polyether derivatives of anyof the foregoing, with said anionic surfactant having a structuralformula as follows:

    R.sub.2 --O--R.sub.3 --SO.sub.3 A

wherein R₂ has a significance as above, R₃ is alkylene or arylene and Arepresents a cation; which comprises the step of treating said aqueousmedia with at least an effective amount of cyclohexanone sufficient todissolve said nonionic surfactant in said cyclohexanone and separatingout said solution of nonionic surfactant in cyclohexanone from aremaining solution of anionic surfactant in water.

A DESCRIPTION OF THE PREFERRED EMBODIMENTS

In more detail the practice of the present invention relates to a methodof separating out nonionic surfactant alcohols of the above type fromanionic sulfonate surfactants prepared therefrom. The ether sulfonateswhich are derived from the alcohol surfactants are prepared by reactingsaid alcohol compound with a hydroxy-containing alkyl sulfonic acid orsalt thereof. The sulfonation reaction may be carried out via a numberof prior art techniques, which will not described in any detail sincetheir description forms no part of the invention.

A number of alcohols, R₂ OH, may be resolved via the process here fromether sulfonates formed therefrom. Such alcohols may include methanol,ethanol, isopropanol, n-propanol, t-butanol, isobutanol, n-butanol,heptyl alcohol, hexyl alcohol, fatty alcohols containing from about 8 toabout 20 carbon atoms such as octyl alcohol, decyl alcohol, laurylalcohol, tridecyl alcohol, tetradecyl alcohol, cetyl alcohol, tallowalcohol, octadecyl alcohol, and eicosyl alcohol.

Other alcohols which may be treated here include the so-called Oxoalcohols from the Oxo process, vinylidene alcohols, Ziegler-type primarylinear alcohols prepared from trialkylaluminum mixtures made by way ofethylene polymerization, subsequent oxidation, and hydrolysis of theresultant aluminum alkoxides as set out in U.S. Pat. No. 3,598,747, andother alcohols of this type. Typical vinylidene alcohols are set out inU.S. Pat. No. 3,952,068 and have the general structure: ##STR1## whereinindividually, x and y are numbers from 1 to 15 and the sum of x and y isin the range of 6 to 16.

Polyhydric alcohols may also be included in the process of theinvention, including such polyhydric alcohols as aliphatic polyhydricalcohols including the aliphatic glycols, such as, for example, ethyleneglycol, propylene glycol, butanediol-1, 4 etc.; and the glycol etherssuch as diethylene glycol, dipropylene glycol and the like. Higherfunctionality polyhydric materials which may be treated include such asglycerol, sorbitol, trimethylolpropane, 1,2,6-hexanetriol,pentaerythritol and the like. Also, suitable are dihydric aromaticmaterials such as bisphenol-A and hydrogenated bisphenol-A. Preferredpolyhydric alcohols are the aliphatic glycols having from 2 to 10 carbonatoms and the aliphatic glycol ethers having from 4 to 20 carbon atoms.

Still other alcohols which may be separated from their ether sulfonatesinclude alkylene glycol mono-lower alkyl ether compounds such asethylene glycol momomethyl ether, ethylene glycol monobutyl ether (ButylCellosolve), propylene glycol monomethyl ether, propylene glycolmonoethyl ether, diethylene glycol monobutyl ether (Butyl Carbitol), andthe like.

Phenols and alkyl substituted phenols may also be employed here. Thus,for example, exemplary phenolic reactants include phenol, nonylphenol,bromophenol, iodophenol, chlorophenol, hydroxyanisole, dinonylphenol,dichlorophenol, cresol, and the like. Particularly preferred are alkylsubstituted phenolic compounds falling within the following structuralformula: ##STR2## where R is an alkyl group containing from 6 to 20carbon atoms or a halo, nitro, or hydroxy alkyl substituted group of thesame chain length, and n is an integer of 1, 2 or 3. Typically R in theabove formula is a C₈₋₂₂ alkyl group.

Another useful class of reactant alcohols from which ether sulfonatesare prepared and which can be treated here are those prepared byalkoxylating any of the above class of alcohols or others. Thus, theabove compounds may be reacted with ethylene oxide, propylene oxide,butylene oxide or higher alkylene oxides having up to 18 carbon atoms ormixtures thereof. When mixed oxides are used, they may be added to thehydroxy or polyhydroxy compound either sequentially to form blockpolyether polyol compounds, or may be mixed and reacted simultaneouslyto form a random, or heteric oxyalkylene chain. The reaction of analkylene oxide and a hydroxy or polyhydroxy compound is well-known tothose skilled in the art, and the base-catalyzed reaction isparticularly described in U.S. Pat. Nos. 3,655,590; 3,535,307 and3,194,773. If diols, triols, tetrols and mixtures thereof arealkoxylated, polyether polyols may be obtained which have a molecularweight of from about 500 to about 10,000. These polyether polyols arewell-known and may be prepared by any known process such as, forexample, the processes described in Encyclopedia of Chemical Technology,Vol. 7, pages 257-262, published by Interscience Publishers, Inc.

A greatly preferred class of hydroxy compounds from which ethersulfonates may be prepared include the compounds falling with thefollowing: ##STR3## where R is a C₁ -C₂₂ radical and n is an integer of1-3, R₁ is hydrogen or an alkyl group of 1-18 carbon atoms, and z is anumber ranging from 1 to 40. Preferably R₁ is hydrogen or methyl and zis 1-10.

Still other alcohols are aralkanols containing a total of from about 7to about 28 carbon atoms. These may be represented by the followingformula: ##STR4## where R₂ is an alkylene group containing 1-22 carbonatoms, and R and n are as just noted. Polyether derivatives of thesecompounds may also be made by appropriate alkoxylation techniques.

Thus, preferred alcohols which may be employed as reactants in preparingether sulfonates and thus must be separated therefrom via the processhere are those having the general formula ROH, where R is a radicalselected from the group consisting of C₁ -C₂₂ alkyl, C₁ -C₂₂ alkenyl,hydroxy or polyhydroxy derivatives of these alkyl or alkenyl compounds,alkaryl radicals containing one or more C₁ -C₁₈ alkyl groups substitutedon said aryl group, and aralkyl radicals containing 7-22 carbon atoms,and polyether derivatives of any of the foregoing.

Ether sulfonates are then prepared from the above alcohols. Thesulfonating agent (sulfoalkylating agent) preferably used is ahydroxyalkyl sulfonic acid or salt thereof. Preferably, the sulfonatingagent is an alkali or alkaline earth metal hydroxy-terminated straightchain alkyl sulfonic acid or salt. Thus, the sulfonating agent employedhere has the following structural formula:

    OHR.sub.3 SO.sub.3 A

where R₃ is a straight or branched alkylene group or an arylene groupsuch as phenylene, which optionally may contain other non-interferinggroups such as halo, nitro, nitrile, etc. groups. More preferably, R₃ isa straight or branched chain unsubstituted alkylene group such asmethylene, ethylene, propylene, butylene, pentylene, hexylene and higheralkylene groups. Most preferably, R₃ contains 1-4 carbon atoms, and in agreatly preferred embodiment is ethylene or propylene. A representshydrogen or a cation, preferably an alkali or alkaline earth metalcation such as sodium, lithium, potassium, calcium, magnesium, cesium,etc.

In the most preferred embodiment of the invention, a process ofseparating ether sulfonates of the formula: ##STR5## from alcoholsformed therefrom is carried out. Here R is a C₁ -C₂₂ alkyl group, n isan integer of 1-3, R₁ is hydrogen or methyl, z is an integer of 1-40, R₃is ethylene or propylene and A is hydrogen or an alkali or alkalineearth metal cation. More preferably A is an alkali or an alkaline earthcation, and most preferably is an alkali metal cation as sodium orpotassium. In this instance an alcoholic compound of the formula:##STR6## when R, n, R₁ and z have a significance as just discussed isreacted with a compound of the formula:

    OHR.sub.3 SO.sub.3 A

where R₃ and A are as just mentioned. The product ether sulfonate isthen separated from the reactant alcohol by the extraction techniqueused here.

The extraction practice here itself utilizing cyclohexanone is carriedout conventionally. One or more extractions may be effected. Moreover,the extraction may be carried at room temperature or even below as itmay likewise be done at temperatures of say 40°-80° C. The cyclohexanoneextractant will selectively remove the alcohol ether sulfonate attemperatures up to the boiling point of the extraction mixture. Again,the extraction method may be employed at atmospheric, sub-atmospheric orsuper-atmospheric pressures. By contact of the mixture of alcohol andether sulfonate with cyclohexanone, the cyclohexanone selectively actsas a solvent for the nonionic surfactant alcohol while the anionicsulfonate stays behind in the aqueous media. The cyclohexanone may bethen distilled from the alcohol while the ether sulfonate may berecovered from the aqueous phase by a number of techniques includingdistillation off of water, precipitation, crystallation or through othermeans.

The following examples specifically illustrate the process of theinvention. It should be understood of course, that these are merelyillustrative and that the invention is not to be limited thereto.

EXAMPLE I

In a separatory funnel were mixed 200 g cyclohexanone, 100 g water and100 g of an aqueous slurry containing the five mole ethoxylate ofnonylphenol (24.8 g) and the ether sulfonate anionic obtained bycondensing this nonionic with sodium hydroxyethylsulfonate. Afterheating to about 50° C. and shaking, two layers formed. The top layerwas removed, and the bottom layer was extracted successively with 200 gand 100 g portions of fresh cyclohexanone. The three extracts werecombined, distilled to remove most of the solvent, then stripped in arotary evaporator to give 28.7 g residue which contained 2.0 g anionic.

The bottom layer was distilled until overhead temperatures reached 100°.The remaining aqueous solution, 87.0 g, contained 17.8 anionic and 0.9 gnonionic.

    ______________________________________                                        SUMMARY OF RESULTS                                                                    Crude    Aqueous   Cyclohexanone                                              Mixture  Solution  Extract                                            ______________________________________                                        Nonionic  24.8 g      0.9 g    26.7 g                                         Anionic   20.5 g     17.8 g     2.0 g                                         ______________________________________                                    

Totals of the two fractions do not add exactly to the starting amountsbecause of handling losses and analytical uncertainties, bu clearly theextraction procedure was very selective in separating the twocomponents.

EXAMPLE II

Cyclohexanone, 400 g, was mixed with 500 g of an aqueous dispersion ofthe four-mole ethoxylate of nonylphenol, 7.94%, and the ether sulfonateof this compound 9.47%, in a separatory funnel.

After removal of the resulting top layer the aqueous bottom layer wasextracted with three 200 g portions of cyclohexanone.

The combined extracts contained 0.09 g sodium which calculates as 2.1 ganionic.

The aqueous layer wad distilled to remove all the cyclohexanone. Theresulting solutions, 283 g, contained 15.8% anionic and 0.3% nonionic.

    ______________________________________                                        SUMMARY OF RESULTS                                                                    Crude    Aqueous   Cyclohexanone                                              Mixture  Solution  Extract                                            ______________________________________                                        Nonionic  39.7 g      0.9 g    not analyzed                                   Anionic   47.4 g     44.7 g    2.1 g                                          ______________________________________                                    

Again it is seen that the extraction procedure is very efficient atseparating the nonionic and anionic components.

The terms "sulfonation" and "sulfonating agent" as herein used are meantto refer to and include both situations involving a conventionsulfonation reaction and a sulfoalkylation reaction.

The invention is hereby claimed as follows:
 1. The method of resolving amixture of a nonionic surfactant and an anionic surfactant existing inan aqueous media, said nonionic surfactant having a structural formulaas follows: ##STR7## where R is a C₁ -C₂₂ alkyl group, n is an integerof 1-3, R is H or CH₃, and z is an integer of 1-40, said anionicsurfactant having a structural formula as follows: ##STR8## where R, R₁,n and z have a significance as above, R₃ is ethylene or propylene and Ais a cation; which comprises the step of treating said aqueous mixturewith at least an effective amount of cyclohexanone sufficient todissolve said nonionic surfactant in said cyclohexanone and separatingout said solution of nonionic surfactant in cyclohexanone from aremaining solution of anionic surfactant in water.
 2. The method ofclaim 1 wherein said treatment is carried out at room temperature. 3.The method of claim 1 wherein said solution of cyclohexanone andnonionic surfactant are separate one from the other by distilling outcyclohexanone.
 4. The method of claim 1 wherein R₃ is ethylene.
 5. Themethod of claim 1 wherein A is an alkali metal cation.